Labyrinthine acoustic metastructures enabling broadband sound absorption and ventilation

There is growing interest in the development of path coiling-based labyrinthine acoustic metamaterials for realizing extraordinary acoustical properties such as low-to-mid frequency sound absorption. We present a subwavelength labyrinthine acoustic metastructure (⁠$≤$3 cm) exhibiting a superior sound absorption with a high bandwidth (more than one octave in the range of 400–1400 Hz). The metastructure is orchestrated of multiple labyrinthine unit cells of different configurations in a hexagonal array, and broadband absorption has been achieved by the dissipation of incident propagating sound waves inside the labyrinthine zigzag channels. Furthermore, the unique design of the metastructure allows for simultaneous air circulation for facilitating natural ventilation and sound absorption. The proposed unique designs may find potential applications in architectural acoustics and noise shielding where simultaneous natural ventilation and noise mitigation are required.